1. Field of the Invention
The present invention relates to a working machine to which a structure for assembling a division type boom is installed.
2. Description of the Related Art
An attachment of a working machine for demolishing buildings, collecting and loading rubble, crushing stones and the like is replaced by other attachment which has a different specification in accordance with a work object (such as demolition, rubble collection and loading), work height (such as a high place and a low place) and the like (refer to Japanese Utility Model Laid-Open No. Sho64-28452).
For example, when a demolition work or the like is performed on a low rise structure, a first attachment A1 having a fundamental separate specification which is a basic specification shown in FIG. 6A is used. When the demolition work or the like is performed on a middle rise structure, a second attachment A2 having an extension separate specification shown in FIG. 6B is used.
As a common configuration among both the first and second attachments A1 and A2, an arm 2 is attached to a front end of a boom 1, a working device (a crusher shown in the figure or a backhoe bucket) 3 is attached to a front end of the arm 2, and a base end part of the boom 1 is attached to a base machine B so as to be raised and lowered around a boom foot pin 4.
The reference numeral 5 denotes a first boom cylinder (a raising and lowering cylinder) provided between the base machine B and the boom 1 for raising and lowering the entire attachment. The reference numeral 6 denotes an arm cylinder provided between the boom 1 and the arm 2 for rotating the arm 2. The reference numeral 7 denotes a working device cylinder provided between the arm 2 and the working device 3 for rotating the working device 3.
In the case of the first attachment A1 in FIG. 6A, the boom 1 is formed by a main boom body 8 on the base end side, and a front boom body 10 coupled to a front end of the main boom body 8 to rotate around a horizontal pin (hereinafter, referred to as a rotation spindle) 9. The front boom body 10 is rotated and folded into a reverse V shape by a second boom cylinder 11 provided between both the boom bodies 8 and 10.
In the second attachment A2 in FIG. 6B, one or more extension boom body 12 (a description will be given to a case of a single extension boom body shown in the figure) is fixed and connected to the main boom body 8 of the first attachment A1 with horizontal pins 13 and 14 on the upper and lower sides in a state that the boom is horizontal. The extension boom body 12 and the front boom body 10 are coupled to each other by the rotation spindle 9, and the second boom cylinder 11 is attached between the extension boom body 12 and the front boom body 10.
A structure of connecting the main boom body 8 and the extension boom body 12 at the time of assembling the second attachment A2 in FIG. 6B or at the time of replacing the first attachment A1 by the second attachment A2 in such a working machine is already shown in Japanese Utility Model No. 2535667.
The above conventional technique is proposed as a structure for connecting the extension boom body 12 to the main boom body 8 in FIG. 6B.
That is, hooks opening upward are provided in a front end part of the main boom body 8, and bosses horizontally extending in the boom width direction are provided in a base end part of the extension boom body 12. In a state that the above hooks and the bosses are engaged with each other, by a “scooping action” of rotating the main boom body 8 upward by the first boom cylinder 5, the extension boom body 12 is rotated in the gradually lowering direction (downward rotation) around a center of the bosses so as to match the upper and lower pin holes with each other.
However, the above conventional technique has a structure that movement of the main boom body and the extension boom body in the folding direction is prevented by the hooks and the bosses. Therefore, when the above structure is used as a connection structure for the main boom body 8 in FIG. 6A or the extension boom body 12 in FIG. 6B and the front boom body 10, the pin holes can be matched but it is possible neither to assemble the second boom cylinder 11 nor to perform work after the connection.
In the conventional technique, it is not possible to facilitate pin hole matching and ensure a folding action for the boom at the same time. Therefore, the conventional technique cannot be applied as a technique for connecting the front boom body.
In addition, there is no other conventionally effective technique with regard to the pin hole matching at the time of connecting the front boom body.
Therefore, the pin hole matching at the time of connecting the front boom body is very troublesome.